chowdsp_polyphase_fir

This repository contains a minimal C/C++ library for computing polyphase FIR filters.

Usage

First, determine your memory requirements:

const auto persistent_bytes = persistent_bytes_required (n_channels, n_taps, interpolation_factor, max_block_size, alignment);
const auto scratch_bytes = scratch_bytes_required (n_taps, interpolation_factor, max_block_size, alignment);

Next, you can create a "state" object:

auto* state = init (n_channels,
                    n_taps,
                    interpolation_factor,
                    max_block_size,
                    allocate_bytes (persistent_bytes, alignment),
                    alignment);

And load in our filter coefficients:

load_coeffs (state, coeffs, n_taps);

Now we're ready to do our processing! We can do polyphase interpolation:

process_interpolate (state,
                     input_buffer,
                     output_buffer,
                     n_channels,
                     n_samples,
                     scratch_data,
                     use_avx);

Or decimation:

process_decimate (state,
                  input_buffer,
                  output_buffer,
                  n_channels,
                  n_samples,
                  scratch_data,
                  use_avx);

License

This code is licensed under the BSD 3-clause license. Enjoy!